Circuit arrangement for multiplex cable telegraphy and telephony



April 7, 1925. 1,532,739

H. FASSBENDER ET AL CIRCUIT ARRANGEMENT FOR MULTIPLEX CABLE TBLEGRAPHY AND TELEPHONY Filed Aug 22, 1921 2 Shoots-5110015 1 April 7, 1925. 1,532,739 H. FASSBENDER ET AL CIRCUIT ARRANGEMENT FOR MULTIPLEX CABLE TELEGRAPH! AND TELEPHONY I Filed Aug. 22, 1921 2 Sheets-Sheet 2 Jnvenfo rs: MM/

eiamw Patented Apr. 7, 1925.

STATE PATENT OFFICE.

HEINRICH FASSBENDER, OF CHARLOTTENBURG, AND ERICH HABANN, OF WAID- MANNSLUST, NEAR BERLIN, GERMANY, ASSIGNORS TO DEUTSCHE TELEPHON- WERKE G. M. B. 11, OF BERLIN, GERMANY.

CIRCUIT ARRANGEMENT FOR MULTIPLEX CABLE TELEGRAPHY AND TELEPHONY.

Application filed August 22, 1921.

To all whom it may concern:

Be it known that we, HEINRICH F ASS- BENDER and Error; HABANN, residing at Charlottenburg and Waidmannslust, near Berlin, Germany, respectively, have invented certain new and useful Improvements in Circuit Arrangements for Multi pleX Cable Telegraphy and Telephony (for which we have filed capplications in Germany on January 20th, 1920, in Switzerland on March 14th, 1921, and in Great Britain on March 15th, 1921), of which the following is a specification.

This invention relates to a circuit arrangement for multiplex telephony or telegraphy by means of high frequency oscillations on lines and has for its object an ar rangement by means of which it is possible to effect a complete separation of the frequencies for the separate receivers in a simple and exact manner, whilst hitherto this was effected by means of tuned oscillating circuits or by artificial loaded lines interposed in the communication line in a more inconvenient manner.

According to the present invention the re ceiver of one station is coupled to the line by means of a circuit arrangement similar to a Wheatstone bridge, this being effected in such a manner that the line is connected to two diagonal points of the bridge and the telegraphic or telephonic receiver (or firstly a transformer, amplifier and so forth) is disposed between the two other diagonal points and in consequence of the tuning of the branches of the bridge receives only a definite group of wave frequencies flowing over the line, whilst the remaining group of frequencies is conducted around the receiver. The invention also relates to the arrangement in cascade of such bridges by means of which an exact wave filtering can be obtained. As a matter of invention two opposite branches of the bridge contain inductance coils with cores of subdivided iron (sheets or wires) in parallel with a condenser whilst the other two branches contain only condensers, whereby either all condensers are of equal capacity and the coils of equal inductance or these elements are inequal but so chosen that the known balanceequation of the Wheatstone-bmdge is satisfied. The division of the iron cores is executed in the well known manner whereby Serial No. 494,389.

the sheets of wires axially extend in the inner hollow space of the coil.

The invention is illustrated diagrammatically in the accompanying drawings.

Figure 1 shows a line I, II which connects the end stations A, D together, which can communicate with each other by means of a high frequency wave. At the same time it is possible for the sub-stations B, C to communicate with each other by a wave of a lower frequency. For the substations the receiver E is placed in a branch of the bridge of which the branches 1, 3 each contain a condenser c and an iron cored inductance coil (Z, and the branches 2, 4, a condenser 0,.

The condensers c, c, are so chosen that they themselves balance the lVheatstone bridge. Therefore, if only these condensers were provided the two terminals of the receiver E would be at the same potential, so that the line current, irrespective of its frequency, would not enter the receiver. As, however, the coils 03 provided with a sub-divided iron core are used a difference in potential is produced-at the terminals of the receiver E in such a manner that the line current, which is below a certain frequency, determined by the degree of sub-division of the iron, passes through the branch 1, the receiver E and the branch 3, whilst for the higher frequency, which is used by the stations A, B, and generally for higher frequencies flowing over the line for a plurality of pairs of stations the bridge remains balanced, because these frequencies, by reason of the iron cores being too little subdivided, do not pass the coils, but by-pass over the parallel condensers. For these frequencies the coils; are practically non-existent. These higher frequencies passing along the line do not enter the receiving branch.

Figure 2 shows a station wherein, by connecting together a number of bridges, corresponding to those shown in Figure 1, a number of frequencies, passing over the conductor, can be separated from one another successively until only a small group of lower frequencies remains for the receiver E. This method has, in comparison with the oscillating circuits operating only to a certain degree, the advantage that a very effective separation of the waves without superimposed waves is attained.

It may be mentioned that in the bridge according to the invention the condensers 0 if their capacity need only be small, may be replaced by ohmic resistances, of which the capacity in this case would be about sufiicient.

Having thus described our invention what we claim as new and desire to secure by Letters Patent is:

1. In an arrangement for multiplex telegraphy or telephony on lines by means of high frequency oscillations, the combination of a line, a stations receiving device and a lVheatstone-bridge by which the said device is connected with the line, the bridge containing in two opposite branches condense-rs and in two other opposite branches condensers in parallel with inductance coils, the latter being provided with subdivided iron cores, two diagonal points, of thebridge being connected with the ll'lCOlTllllgfiJlCl outgoing part of the line whilst two other diagonal points are connected with the lead ing-to wire of the said receiving device, whereby the range of waves entering the receiving device is separated by the graduation of the iron core subdivision from a higher range of waves not entering the receiving device, substantially as described.

2. In an arrangement for multiplex telegraphy or telephony on lines by means of high frequency oscillations, the combination of a line, a stations receiving device and a cascade arrangement of Wheatstone-bridges by which the said device is connected with the line, each bridge containing in two opposite branches condensers and in two other opposite branches condensers in parallel with inductance coils, the latter being provided with subdivided iron cores, two diagonal points of each bridge being connected with two diagonal points of the foregoing bridge and two other diagonal points of each bridge being connected with two diagonal points of the next following bridge, two diagonal points of the first bridge of the cascade being connected with the incoming and outgoing part of .the line whilst two diagonal points of the last bridge of the cascade are connected with the leading-to wire of the said receiving device, whereby the range of waves entering the receiving device is gradually diminished by the graduation of the iron core-subdivision from bridge to bridge, substantially as described.

In testimony whereof we have aflixed our signatures in presence of two witnesses.

PROF. DR. HEINR. FASSBENDER. ERICI-I HABANN.

Witnesses: I

LOTHAR WERNER, VILLI DUFF. 

